1. Field of Invention
This invention pertains generally to inline optical sensors and, more particularly, to an inline optical sensors having a modular flowcell that can accommodate different line sizes and different optical pathlengths.
2. Related Art
Flowcells are used widely in inline optical sensors for monitoring the properties of product streams in the biotechnology field and in other sanitary applications. The flow lines employed in such applications typically have internal diameters ranging in size from ⅛ inch to ¾ inch (approximately 3 mm to 19 mm), and heretofore it has been necessary to manufacture flowcells with passageways corresponding to the different line sizes. With passageways of smaller diameters, proper drainage can be a problem even if the flowcell is mounted with the passageway extending vertically.
Such instruments typically have optical windows positioned on opposite sides of the product stream, with a light source outside one of the windows for directing a beam through the stream and a detector outside the other for receiving the beam. The light can be in the ultra violet, visible or near infrared spectrums. The length of the optical path through the fluid stream is determined by the spacing between the windows, and heretofore the only way to change the pathlength significantly has been to use windows of different lengths. That requires a different pair of windows for every pathlength, and varying an optical pathlength from 0.5 mm to 20 mm could, for example, require as many as seven sets of windows. Moreover, the O-ring gaskets typically utilized in sealing such windows can be difficult to sanitize with commonly used clean-in-place (CIP) and steam-in-place (SIP) cleaning procedures.
Another problem with optical sensor flowcells is alignment of the light source and detector along the optical axis. While some existing flowcells may permit proper axial alignment, radial alignment is generally not possible.